Presently known systems for providing uninterruptible power to flight control computer systems include power supply systems having capacitor banks to store energy and to supply power to the flight control computer system during primary power interruptions.
Additionally, flight control computers have in the past utilized diode-isolated multiple power supplies. In at least one of such diode-isolated power supplies, .[.nickle.]. .Iadd.nickel .Iaddend.cadmium batteries were employed for energy storage.
In addition, power supplies employing multicoil transformers for maintaining DC power upon loss of one or more of the AC primary sources, are also well known.
However, each of these systems is hampered by substantial disadvantages. For example, capacitor banks for power storage typically need to be very large in order to provide a reasonably adequate power storage time. Moreover, the storage capacity of the capacitor banks deteriorates with the failure of individual capacitors of the bank. Such failures are difficult to detect. Moreover, the capacitors are flammable and can be dangerous.
In the case of diode-isolated multiple source power supplies, a ground fault at the flight control computer would simultaneously affect each of the system power sources. Also, a single over-voltage transient can pass through the diode source connection and detrimentally affect all computers tied to that bus. Additionally, no capability exists in such a system to establish power source priorities.
Diode-isolated dual-source supplies featuring batteries have all the disadvantages of diode isolated multiple prime-source supplies, and others in addition. For example, such sources are subject to the added difficulty of needing to measure the charge state of the .[.nickle.]. .Iadd.nickel .Iaddend.cadmium batteries employed. Beyond this, the .[.nickle.]. .Iadd.nickel .Iaddend.cadmium battery packs are heavy and require considerable maintenance. Finally, multicoil transformer supplies offer no over-voltage protection; and, a short circuit in any one of the coils can cause a complete loss of power affecting the entire computer system.
An object of the invention is to provide an electric power distribution and load transfer system, which applies any of a plurality of separate power sources, each of the units being isolated with respect to each other.
According to the invention, an electric power distribution and load transfer system is provided for insuring that at least one of several power sources connected to corresponding lead transfer units is fault free in the case of a single one of said load transfer units failing.